Mercury rectifier tube



June 9, 1953 R. s. TICE MERGURY RECTIFIER TUBE 2 Sheets-Sheet l Filed March '7, 1950 LOAD ANODE ca'ruonz INVENTOR.

- 1 :0,! w. r/ct.

BY g M y June 9, 1953 R. s. TICE MERCURY RECTIFIER TUBE 2 Sheets-Sheet 2 Filed March '7 1950 INVENTOR. REUB EN 5. TICE BY fl zg M v ATTORN E Y6 Patented June 9, 1953 MERCURY RECTIFIER TUBE Reuben S. Tice, Monterey, Calif., assignor of sixty-five per cent to George Hart, Pebble Beach, Calif.

Application March 7, 1950, Serial No. 148,075

This invention relates to a mercury rectifier tube or to a dielectrically iginited mercury tube. Such tubes have also been called ion-discharge tubes and have had other names.

One of the main objects of this invention is the provision of a dielectrically ignited mercury tube that is capable of operating at high efiiciency for a period of time that is many times longer than has heretofore been deemed possible.

Some years ago it was discovered that by placing a metal band on the outside of a high vacuum mercury tube and by applying a potential of say about to 8 kv. to this band, a potential would be impressed through the glass dielectric that would break the'miniscus line below the surface of the mercury cathode and cause the mercury to ionize at this point and fire to a carbon or graphite anode in the circuit. If the action was continued on an alternating current cycle, the tube would be automatically extinguished at the end of every half cycle. Subsequently, the conclusion was reached that if the tube could be ignited at a predetermined phase angle, the tube would act as a valve, automatically limiting the amount of current passed and rectified due to the time constant.

The results of experiments and developments along the above lines have resulted in the production of tubes that will operate with reason ably good efficiency for 'a maximum of about fifty hours. However, after that period the me'rcury would become contaminated and the tube would cease firing. Most dielectrically ignited tubes developed before 1940 would operate for only from four or five hours to ten hours.

The present tube will operate at high effi-- ciency for an indefinite period beyond 1000 hours in the absence of any defect in the glass or other 1 provision of a dielectrically ignited mercury rectifier tube in which both the cathode and anode are mercury, and in which the cathode isautomatically cleared of contamination and in, which there is no short circuiting of the current between the cathode and anode.

An added object of the invention is the pro} vision of a dielectrically ignited mercury rectifier tube that is particularly adapted for vari- 13 Claims. (Cl. 313-170) 2 able output and in which there is an anode pool of mercury and a cathode pool of mercury and 1 a substantially continuous flow of mercury from the surface level of the cathode pool and at one edge thereof to the anode pool to efi'ect a selfclearing of said cathode pool of impurities whereby the major portion of the surface of said cathode pool will be clean and the' said impurities will tend to move to the anode pool,

which is comparatively free from adverse effects of contamination;

In the drawings,

Fig. 1 is a vertical cross-sectional view taken Fig. 3 is a fragmentary view of the top of a tube, slightly modified with the addition of a carbon anode disk, the tube being in cross-sec- I tion and a simple circuit being indicated. 1

Fig. 4 is a fragmentary view of a portion of the tube at one point around theannular cathode pool showing a filament over said pool. The 7 glass of the tube is in cross-section.

In detail, in the preferred form, the body of the tube may be formedof glass and is preferably generally bulbous, having a substantially hemispherical upper portion l and ,a generally conical lower portion 2 in which the sides extend convergently downwardly to a sump por-" tion'3. The lower part of said sump portion is preferably a Kovar electrode cup sealed along.

its upper edges to the glass upper part 5 of the sump that is in downward continuation of the portion 2.

Along the juncture between the upper and lower portions of said tube and within the same is an upwardly opening annular channel or trough 6, one side I of which is in downward continuation of the hemispherical portion I of the tube, and the other or inner side 8 of which I constitutes a weir connected with the outer side 1 by bottom 9. This channel is normally filled, Withmercury and is the cathode pool and also functions as a collector for the mercury condensed on the hemispherical inner surface of. the.

tube.

6 may have a rounded bead 10 along its upper edge over which the mercury II in the channel is adapted to spill when the channel is filled to overflowing, 1

At equally spaced points (3 points shown in The weir 8 or the inner side of said channel sides of which recesses may project downwardly and outwardly of said channel. An electrode it of Kovar, tungsten or any other suitable material extends upwardly through the bottom of each recess l2 into the mercury II that fills the same. Said electrodes may be connected outside said tube by any suitable conductor I4 (Fig. 2) that, in turn, may be connected with an alternating current when the tube is in ope-ration. While the drawing shows 3 electrodes, the tube will work with any reasonable number from 1 up.

The annular pool H of mercury constitutes the cathode pool, as has been mentioned, and is at the level above that of the anode pool, as will later be described more in detail.

The upper edges of the downwardly convergent sides of the lower conical portion 2 of the tube may connect with the bottom of the channel 6 adjacent the inner side 8 of said channel.

A spirally extending upwardly opening trough I is formed in the tapered sides of the lower portion of the tube, which trough extends from a point adjacent said channel 6 to the lower end of the tube with the upper coil or end portion of said trough positioned to receive the mercury that spills over the wei-r 8.

The lower end of trough I5 terminates at or adjacent the upper part 5 of the sump that is at the lower end of the tube.

An anode pool 20 of mercury fills the anode cup and normally would rise into part 5 to substantially fill the latter.

The trough 15 may have an incline of about five degrees relative to horizontal, and the bottom of said trough is formed with upwardly opening recesses or dimples 2| at equally spaced points therealong, each adapted to receive mercury as it flows down the trough. The effect of these recesses is to cause the mercury to flow downwardly to the anode pool in a series of steps and in spacedcharges due to the cohesion and the surface'tension characteristics of the mercury. This prevents a direct short circuit between the cathode and anode pools.

, Between each of the cathodes I3 a silver oxide band 22 i painted on the exterior of the tube, about half the width of each band being above, and halfbelow, the level of mercury H ofthe cathode pool, which bands may be connected by conductors 23 with a source of potential for start ing the firing action. Gold oxide, graphite, or other conducting paint may be used instead of silver oxide for the bands, although silver oxide is preferable from the standpoint of economy and permanency.

The bands 22 are preferably flash fired during construction of the tube thus eliminating the air. dielectric contact between the metal film and the glass with corresponding elimination of the corona effect that would exist were a metal band employed instead of the oxide film. Also, the bands 22 are preferably covered with a thin coat of silicone varnish, I eliminating corona effects normally present externally of the tube, which otherwise would result in requiring a higher potential to energize the ignition circuit on the tube.

In operation, the tube operates smoothly at a potential from 14 volts to the full voltage applied across the tube, and handles 5 kvfsatisfactorily in the size heretofore employed, in which the diameter of the cathode pool from center to center of the pool at each side of the tube is substantially five inches, the relative proportions and annular receptacle 35.

4 shapes corresponding with those shown in the drawings. The current, of course, is proportional to the areas of the cathode and anode pools and to the cooling surfaces of the condenser or bulb enclosing the anode and cathode.

Mercury tubes seem to have an aversion to firing into an inductive or capacitative load and may act erratically if some sort of ballastload is not used. It is, therefore, preferable to place an electrode, such as a carbon anode disk 25 in the tube, as seen in Fig. 3, wherein the top portion of the tube of Fig. 1 is indicated and is designated 26. By energizing this disk with an external load of say 50 watts, the objection will be overcome regardless of the normal external load between the main pools. A third pool of mercury could be used inside the tube instead of the carbon disk. A simple circuit is indicated in Fig. 3 where electrode 25 or the equivalent is used.

By placing a filament 2'! (Fig. 4), above the mercury level in the cathode pool with a suitable load circuit between said filament and the oathode, the tube may be used as a half wave rectifier, without external resistance and without complicated ignition circuits.

The present tube has many uses, several bein for operating D. C. motors at various speeds from A. C. lines; for controlling the heat of heating elements by a time load factor, such a the elements in a domestic or commercial electric range, such control being comparable with that of a valve in a gas range; for a square wave invertor up to 2000 cycles; for various types of electrically actuated impact tools, etc.

In Fig. 5 a modified form of the invention is shown, and while the tube illustrated operates satisfactorily, it would be more expensive to make than the form shown in Fig. 1.

The tube of Fig. 5 may also be formed of glass and has a main cylindrical upper portion 33 having atop wall 3! and a downwardly convergently extending lower end portion 32 that terminates in a Kovar cup 33.

An annular upwardly opening channelor weir 34 is around the inner side of the portion 30 spaced above the tapered lower end portion 32, said channel being preferably integrally united with the walls of portion 30 for'draining of condensed'mercury vapor into the same, as occurs in the form shown in Fig. 1.

Centrally within the tube 30 an annular receptacle 35 is provided, which receptacle is supported within said tube by a hollow glass cylinder 36 that is secured integrally with the top wall3l through which it opens to the atmosphere. The lower end of cylinder 36 is sealed shut by a lower end wall 31, and the lower end portion of said cylinder forms the inner side wall of the The receptacle 35 is spaced within a second glass receptacle 38 having a cylindrical upper wall 39 concentric with and spaced outwardly of the outer side wall 40 of receptacle 35; Any suitable lugs of glass may connect the receptacle 35 with the second receptacle 38 for holding them in spaced relation. 7 Cylindrical wall 39 has a downwardly convergentlyextending bottom wall 4| that may have a plurality of spaced horizontal troughs 42 formed therein, the upper one being below the space between the outer cylindrical wall 39 and the outer side wall of the annular receptacle 35. The lower end of bottom wall is open as at 43.

The Kovar cup 33 is spaced below the opening 43 and coaxial therewith.

The spaced annular troughs will cause the mercury to flow from the cathode pool to the anode pool in spaced charges, as it were, thus preventing direct short circuiting.

One or more metal bands 44 may be secured to the inner side of the lower end of cylinder 36 weir to a point above the central receptacle where the mercury discharged from the lower end of said drain trough will strike a deflector 49 carried on the central cylinder 36 above receptacle 35. The mercury drained from trough 48 is discharged into the mercury of pool but does not drain over the surface of the cylinder 36 around the plates 44.

Referring to the manner of operation of the.

preferred form shown in Figs. 1 to 4 inclusive, when the tube is fired, the mercury from the cathode and anode pools will condense at the top of the tube and will run into channel 8 keeping the cathode pool ll filled. Upon overflowing, any contamination of the mercury that may have been in the original mercury in the cathode pool will move to the inner side of the cathode pool and will usually flow over the weir 8 into the upper end of the spiral trough 15 for flowing down the trough, in steps, tothe anode pool. Thus the surface of the-cathode pool will be kept clean which is essential to a continued eflicient operation of the tube for a substantial length of time of say from 1000 hours upward, although in view of the present relatively short life of tubes intended to operate in the same manner as the present tube, even five to six hundred hours of operation would be considered a substantial improvement.

The fact that the cathode pool is around the horizontal large perimeter of the body of the tube provides a large cathode volume for supplying the anode, and the hemispherical condensing surface I of the tube provides a large cooling area. It has already been pointed out that the spiral trough with the spaced depressions in the bottom thereof insure interruption in the'path of travel of the mercury between the cathode and anode pools so as to eleminate any chance of a direct shorting in the circuit and consequent discontinuance of the operation of the tube.

In the forms shown in Figs. land 5, it will be seen that both forms provide an annular cathode pool at a level above the anode pool, and in both forms the overflow from the cathode pool is over an annular lip or side wall with the metal plates or metal oxide around the cathode pool being at the side opposite that over which the mercury is adapted to spill for passage to the anode pool. In both forms of the invention, the mercury is condensed on the inside of the upper portion of the tube and drains into a collector or trough around the inner side of said tube. In Fig. '1 this trough holds the cathode pool while in Fig. 5 it is conducted from the trough into the cathode pool.

In the forms shown in Figs; 1 and 5, means is provided for interrupting the flow of mercury from the cathode to the anode pool, and in both instances thefpath between the cathode and anode pools includes an upwardly opening trough extending around the inner sides of a downwardly convergently extending generally conical wall.

In both forms of the invention there is a continuous distillation of mercury and a continuous feeding of the condensed mercury into the oathode pool and an intermittent feeding ofmercury from the cathode pool to the anode pool, it being understood that the word intermittent is here used to distinguish from that of a solid stream of any dimension or volume such as would occur at times were there to be merely a conventional drain between the cathode and anode pools with no means for insuring a break in the stream at any time the merucry overflows the cathode tube.

The present invention is not to be confused with conventional lights employing. a mercury are as a light source wherein an arc is maintained by electrical discharge through the tube.

The invention. above explained is a variable output rectifier tube that is ignited every half cycle by a circuit external to the tube.

Mercurial contamination does not effectively limit the life of tubes such as are known to the trade as Cooper-Hewitt tubes, and their like, for the reason that once an arc is established in such tubes it is continuous, and contamination would only make them a few cycles slower to ignite. In the present invention, the tube must instantaneously igniteon every half cycle up to the highest frequency at which the tube operates. Therefore, mercurial contamination is a vital factor in the life of the present tube and in any that would be intended to operate in the same manner for the same use.

There are so-called mercury rectifier tubes that are alleged to give upward of one thousand hours satisfactory operation, but these are tubes that have filaments with some type of solid high current rectification, the peak inverse voltage that the tubes will withstand is 1000, whereas a tube of the present invention will withstand 6000 volts. Also the maximum D. C. rating of conventional mercury rectifier tubes is 20 amperes, whereas the tube of the present invention is limited only by its cooling capacity and the 7 pool and an anode pool, said cathode pool being annular, means for supporting said cathode pool spaced around said anodev pool with the level of said cathode pool above-that of said anode pool,

means for applying anelectrical potential across said pools for causing vaporization of mercury in the latter, said body including a condensing surface above said pools for condensing the vaporized mercury and means for conducting the mercury condensate to said annular cathode pool to fill the latter for overflow to said anode pool.

2. In a mercury rectifier tube having a hollow body; a pair of spaced pools of mercury supported within said body providing a cathode pool and an anode pool, said cathode pool being annular, means for supporting said cathode pool spaced around said anode pool with the level'of said cathode pool above that of said anode pool, means for applying an electrical potential across said pools for causing vaporization of mercury in the latter, said body including a condensing surface above said pools for condensing the vaporized mercury and means for conducting the mercury condensate to said annular cathode pool to fill the latter for overflow to said anode pool, the means for supporting said cathode pool including an annular channel having opposite annular sides and a bottom, one of said sides being lower than the other to provide for said overflow over the lower of said sides.

3. In a mercury rectifier tube having a hollow body; a' pair of spaced pools of mercury supported within said body providing a cathode pool and an anode pool, said cathode pool being an nular, means for supporting said cathode pool spaced around said anode pool with the level of said cathode pool above that of said anode pool, means for applying an electrical potential across said pools for causing vaporization of mercury in the latter, said body including a condensing surface above said pools for condensing the vaporized mercury and means for conducting the mercury condensate to said annular cathode pool to fill the latter for overflow to said anode pool,

the means for supporting said cathode pool ineluding an annular channel having opposite annular sides and a bottom, one of said sides bein lower than the other to provide for said overflow over the lower of said sides, a Kovar cup closing the lower end of said body and comprising the means for supporting said anode pool.

4. In a mercury rectifier tube having a hollow body; a pair of spaced pools of mercury supported within said body providing a cathode pool and an anode pool, said cathode pool being annular, means for supporting said cathode pool spaced around said anode pool with the level of said cathode pool above that of said anode pool,

in the latter, said body including a condensing surface above said pools for condensing the vaporized mercury and means for conducting the mercury condensate to said annular cathode pool to fill the latter for overflow to said anode pool, the means for supporting said cathode pool in-- cluding an annular'weir formed on the inner side of said body and extending therearound and having a free annular upper edge over which the said mercury is adapted to overflow.

5. In a mercury rectifier tube having a hollow body; a pair of vertically spaced pools of mercury supported within said body providing a cathode pool and an anode pool, means for so supporting said pools, the upper pool of said pair being the cathode pool and the means for supporting it above said anode pool comprising an annular upwardly opening channel having'opposed sides and a bottom, the? radially outer side of said channel being formed in continuation of a side of said body and the radially inner side terminating in a circular edge over which the mercury in said cathode pool is adapted to overflow into said anode pool.

6. In a mercury rectifier tube having a hollow body; a pair of vertically spaced pools of mercury supported Within said body providing a cathode pool and an anode pool,'means for so supporting said pools, the upper pool of said pair being the cathode pool and the means for supporting it above said anode pool comprising an annular upwardly opening channel having 0pposed sides and a bottom, the radially outer side of said. channel being formed in continuation of a side of said body and the radially inner side terminating in a-circular edge over which the '7. In a mercury rectifier tube having a hollowbody; a pair of vertically spaced pools of mercury supported within said body providing a cathode pool and an anode pool, means for so supporting said pools, the upper pool of said pair being the cathode pool and the means for supporting it above said anode pool comprising an annular upwardly opening channel having opposed sides and a bottom, the radially outer side of said channel being formed in continuation of a side of said. body and the radially inner side terminating in a circular edge over which the mercury in said cathode poo-l is adapted to overflow into said anode pool, the sides of said body below said channel extending convergently downwardly from said channel and the means for supporting said anode pool including a Kovar cup closing the lower end of the body at the convergent ends of the sides of said body below said channel.

8. In aImercury rectifier tube having a hollow body; a pair of spaced pools of mercury within said body providing a cathode pool and an anode pool, means for so supporting said pools within said body with the level of said cathode pool substantially above that of said anode: pool, the means for supporting said cathode pool including a weir over which mercury is adapted to overflow when said tube is in operation, an inclined trougli' between said cathode pool and said anode pool for conducting said overflow from said cathode pool to said anode pool, said trough being formed with recesses in-the' bottom thereof for obstructing the continuity of flow of mercury from said cathode pool to said anode pool to prevent a direct short within said body at the juncture between said upper and said lower portions, the radially outer side of which is in downward continuation of said hemispherical portion and the radially inner side of which terminates ina free upper edge over' which mercury is adapted to overflow into the upper end of said conical lower portion, a Kovar cup closing said cup and said channel being filled with mercury, means for applying an electrical potential across said pools to efiect vaporization of said mercury in said pools and said hemispherical portion providing a condensing surface for said vaporized mercury and for conducting the mercury condensate into said channel for causing overflow thereof.

10. A mercury rectifier tube comprising a generally bulbous hollow body having a substantial- 1y hemispherical upper portion and a generally conical line portion extending convergently downwardly from the lower end of said upper portion, an upwardly opening annular channel within said body at the juncture between said upper and said lower portions, the radially outer side of which is in downward continuation of said hemispherical portion and the radially inner side of which terminates in a free upper edge over which mercury is adapted to overflow into the upper end of said conical lower portion, a Kovar cup closing said cup and said channel being filled with mercury, means for applying an electrical potential across said pools to effect vaporization of said mercury in said pools and said hemispherical portion providing a condensing surface for said vaporized mercury and for conducting the mercury condensate into said :5

channel for causing overflow thereof, the said conical lower portion being formed with an upwardly opening spiral trough extending from said channel to said Kovar cup for conducting the overflow of mercury from said channel to said cup, and the bottom of said channel being formed with depressions providing baflles to interrupt the continuity of flow of mercury from said channel to said cup to prevent a direct short circuit between said pools.

11. A mercury rectifier tube comprising a generally bulbous hollow body having a substantially hemispherical upper portion and a generally conical line portion extending convergently downwardly from the lower end of said upper portion, an upwardly opening annular channel within said body at the juncture between said upper and said lower portions, the radially outer side of which is in downward continuation of said hemispherical portion and the radially inner side of which terminates in a free upper edge over which mercury is adapted to overflow into the upper end of said conical lower portion, a Kovar cup closing said cup and said channel being filled with mercury, means for applying an electrical potential across said pools to effect vaporization of said mercury in said pools and said hemispherical portion providing a condensing surface for said vaporized mercur and for conducting the mercury condensate into said channel for causing overflow thereof, a solid anode supported within the said upper portion, a metallic band on the outer side of said body projecting above and below the level of mercury in said cathode pool, and means for connecting said solid electrode and said cathode pool in an electrical circuit.

12. In a mercury rectifier tube having a hollow body; a pair of spaced pools of mercury supported within said body providing a cathode pool and an anode pool respectively, the level of said cathode pool being positioned at a higher elevation than the level of said anode pool, means for applying an electrical potential across said pools for causing vaporization of mercury in the for applying an electrical potential across said pools for causing vaporization of mercury in the latter, said body including a condensing surface above said cathode pool for condensing the vaporized mercury and for conducting condensate to said cathode pool to fill the latter for overflow to said anode pool, means in aid body intermediate said pools for receiving the condensate from said cathode pool and for conducting said condensate to said anode pool.

REUBEN S. TICE.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Spencer May 2, 1944 Number 

